Resonance apparatus for processing electrical loss using conductive material and method for manufacturing the same

ABSTRACT

A resonance apparatus that processes an electrical loss using a conductive material and a method of manufacturing the resonance apparatus are provided. The resonance apparatus includes a lower electrode formed at a predetermined distance from a substrate, and a piezoelectric layer formed on the lower electrode. The resonance apparatus further includes an upper electrode formed on the piezoelectric layer, and a conductive layer formed on the upper electrode or the lower electrode.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit under 35 USC §119(a) of KoreanPatent Application No. 10-2012-0100437, filed on Sep. 11, 2012, in theKorean Intellectual Property Office, the entire disclosure of which isincorporated herein by reference for all purposes.

BACKGROUND

1. Field

The following description relates to a resonance apparatus thatprocesses an electrical loss using a conductive material and a method ofmanufacturing the resonance apparatus.

2. Description of Related Art

A film bulk acoustic wave resonator (BAWR) refers to an acoustic devicecapable of resonating at a predetermined frequency. The film BAWR mayuse molybdenum (Mo), ruthenium (Ru), and/or tungsten (W), as anelectrode.

Performance of a resonator may be reduced, and accordingly, frequencyefficiency of a mobile terminal including the resonator may be reduced.For example, if an electrical loss is generated in the resonator,interference between a transmitted signal and a received signal mayincrease. Accordingly, the mobile terminal may need a larger fractionalband gap to process inter symbol interference (ISI), thereby wastingfrequency resources.

SUMMARY

In one general aspect, there is provided a resonance apparatus includinga lower electrode formed at a predetermined distance from a substrate,and a piezoelectric layer formed on the lower electrode. The resonanceapparatus further includes an upper electrode formed on thepiezoelectric layer, and a conductive layer formed on the upperelectrode or the lower electrode.

In another general aspect, there is provided a film bulk acoustic filterincluding resonators formed on a substrate, and an electrode connectionunit configured to connect an upper electrode to a lower electrode, ofat least one of the resonators. The film bulk acoustic filter furtherincludes a grounding unit configured to connect the upper electrode andthe lower electrode to ground, and a pad formed on the substrate andconfigured to connect the upper electrode and the lower electrode to anexternal terminal. The film bulk acoustic filter further includes aconductive layer forming unit configured to form a conductive layer onthe electrode connection unit, or the grounding unit, or the pad, or anycombination thereof.

In still another general aspect, there is provided a method ofmanufacturing a resonance apparatus, including forming a lower electrodeat a predetermined distance from a substrate, and forming apiezoelectric layer on the lower electrode. The method further includesforming an upper electrode on the piezoelectric layer, and forming aconductive layer on the upper electrode or the lower electrode.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a resonance apparatus.

FIG. 2 is a diagram illustrating an example of an operation of vapordepositing a conductive material adjacent to a resonance unit.

FIG. 3 is a diagram illustrating another example of a resonanceapparatus including a loss compensation layer.

FIG. 4 is a diagram illustrating still another example of a resonanceapparatus including a reflective layer.

FIG. 5 is a diagram illustrating yet another example of a resonanceapparatus including a loss compensation layer and a reflective layer.

FIG. 6 is a diagram illustrating still another example of a resonanceapparatus.

FIG. 7 is a diagram illustrating yet another example of a resonanceapparatus including a loss compensation layer.

FIG. 8 is a block diagram illustrating an example of a film bulkacoustic filter.

FIG. 9 is a diagram illustrating another example of a film bulk acousticfilter.

FIG. 10 is a diagram illustrating an example of an electrode connectionunit in a film bulk acoustic filter.

FIG. 11 is a flowchart illustrating an example of a method ofmanufacturing a resonance apparatus.

FIG. 12 is a flowchart illustrating another example of a method ofmanufacturing a resonance apparatus.

FIG. 13 is a flowchart illustrating still another example of a method ofmanufacturing a resonance apparatus.

Throughout the drawings and the detailed description, unless otherwisedescribed, the same drawing reference numerals will be understood torefer to the same elements, features, and structures. The relative sizeand depiction of these elements may be exaggerated for clarity,illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. Accordingly, various changes,modifications, and equivalents of the systems, apparatuses, and/ormethods described herein will be suggested to those of ordinary skill inthe art. The progression of processing steps and/or operations describedis an example; however, the sequence of steps and/or operations is notlimited to that set forth herein and may be changed as is known in theart, with the exception of steps and/or operations necessarily occurringin a certain order. Also, description of well-known functions andconstructions may be omitted for increased clarity and conciseness. Likereference numerals designate like elements throughout the drawings.

It is understood that the features of the disclosure may be embodied indifferent forms and should not be constructed as limited to theexample(s) set forth herein. Rather, example(s) are provided so thatthis disclosure will be thorough and complete, and will convey the fullscope of the disclosure to those skilled in the art. The drawings maynot be necessarily to scale, and, in some instances, proportions mayhave been exaggerated in order to clearly illustrate features of theexample(s). When a first layer is referred to as being “on” a secondlayer or “on” a substrate, it may not only refer to a case where thefirst layer is formed directly on the second layer or the substrate butmay also refer to a case where a third layer exists between the firstlayer and the second layer or the substrate.

FIG. 1 is a diagram illustrating an example of a resonance apparatus100. The resonance apparatus 100 includes an air-gap cavity structureincluding a lower electrode, an upper electrode, and a piezoelectriclayer, which are arranged on an upper portion of a substrate, with apredetermined cavity arranged between the substrate and the lowerelectrode. According to FIG. 1, the resonance apparatus 100 includes asubstrate 101, a lower electrode 102, a piezoelectric layer 104, anupper electrode 105, and conductive layers 106 and 107.

The substrate 101 may be doped with silicon (Si). For example, thesubstrate 101 may include a Si wafer.

The lower electrode 102 is formed over an upper portion of the substrate101, and is separated by a predetermined distance from the upper portionof the substrate 101. For example, the lower electrode 102 may be madeof molybdenum (Mo), ruthenium (Ru), tungsten (W), and/or otherconductive materials known to one of ordinary skill in the art. Thelower electrode 102 may be used as an input electrode to inject anelectrical signal, such as a radio frequency (RF) signal, into thepiezoelectric layer 104, and/or as an output electrode to output anelectrical signal from the piezoelectric layer 104. For example, if thelower electrode 102 is an input electrode, the upper electrode 105 is anoutput electrode. If the lower electrode 102 is an output electrode, theupper electrode 105 is an input electrode.

A cavity 103 is formed between the lower electrode 102 and the substrate101. Therefore, the lower electrode 102 is separated from the substrate101 by as much as the cavity 103.

The upper electrode 105 is formed on an upper portion of thepiezoelectric layer 104. For example, the upper electrode 105 may beformed by vapor depositing Mo, Ru, W, and/or other conductive materialsknown to one of ordinary skill in the art, on the upper portion of thepiezoelectric layer 104. The upper electrode 105 may be used as an inputelectrode to inject an electrical signal, such as an RF signal, into thepiezoelectric layer 104, and/or as an output electrode to output anelectrical signal from the piezoelectric layer 104.

The piezoelectric layer 104 is formed on an upper portion of the lowerelectrode 102, and on the upper portion of the substrate 101. Forexample, the piezoelectric layer 104 may be formed by vapor depositingan aluminum nitride (AlN), a zinc oxide (ZnO), or a lead zirconatetitanate, on the upper portion of the lower electrode 102, and on theupper portion of the substrate 101. The piezoelectric layer 104 convertsan electrical signal input from the lower electrode 102 or the upperelectrode 105 into an acoustic wave.

In more detail, when a temporally changing electric field is induced,the piezoelectric layer 104 converts the electrical signal into aphysical oscillation. The piezoelectric layer 104 converts the physicaloscillation into the acoustic wave. The piezoelectric layer 104generates the acoustic wave to be a bulk acoustic wave based on theinduced electric field in a same direction as an oscillation directionin an oriented piezoelectric film.

As shown in FIG. 1, the conductive layers 106 and 107 are formed on alower portion of the lower electrode 102 and an upper portion of theupper electrode 105, respectively. For example, the conductive layers106 and 107 may be formed by vapor depositing a conductive material onthe lower portion of the lower electrode 102 and the upper portion ofthe upper electrode 105, respectively. The conductive material mayinclude, for example, silver (Ag), copper (Cu), gold (Au), Al, calcium(Ca), W, zinc (Zn), nickel (Ni), iron (Fe), platinum (Pt), carbon steel,lead, grain-oriented electrical steel, manganin, constantan, stainlesssteel, and/or graphite.

In more detail, the conductive layers 106 and 107 may be formed by vapordepositing the conductive material adjacent to a resonance unitcorresponding to a portion of the upper electrode 105 and/or the lowerelectrode 102. For example, the conductive layers 106 and 107 may beformed by vapor depositing the conductive material at an interfacebetween the resonance unit and a connection unit corresponding to aremaining portion of the upper electrode 105 and/or the lower electrode102, such that the conductive material is formed as close as possible tothe resonance unit. The vapor depositing of the conductive material atthe interface between the resonance unit and the connection unit will bedescribed with reference to FIG. 2.

In another example, the conductive layer 106 may be formed by vapordepositing the conductive material on the upper portion or the lowerportion of the lower electrode 102. In more detail, the conductive layer106 may be formed by vapor depositing the conductive material on thelower portion of the lower electrode 102 that corresponds to the upperportion of the substrate 101, as shown in FIG. 1. Alternatively, theconductive layer 106 may be formed by vapor depositing the conductivematerial on the upper portion of the lower electrode 102 thatcorresponds to a lower portion of the piezoelectric layer 104.

In this example, the conductive layer 107 may be formed by vapordepositing the conductive material on the upper portion or a lowerportion of the upper electrode 105. In more detail, the conductive layer107 may be formed by vapor depositing the conductive material on thelower portion of the upper electrode 105 that corresponds to the upperportion of the piezoelectric layer 104.

In still another example, the conductive layer 106 may be formed at theupper electrode 105, whereas the conductive layer 107 is formed at thelower electrode 102.

The conductive layer 106 and the conductive layer 107 may be formed byvapor depositing the conductive material so that the conductive layer106 and the conductive layer 107 are not shorted with each other. Forexample, if the conductive layer 106 is formed on the upper portion ofthe lower electrode 102, and the conductive layer 107 is formed on thelower portion of the upper electrode 105, a short between the conductivelayer 106 and the conductive layer 107 may occur. Therefore, if theconductive layer 106 is formed on the upper portion of the lowerelectrode 102, the conductive layer 107 is formed on the upper portionof the upper electrode 105. If the conductive layer 106 is formed on thelower portion of the lower electrode 102, the conductive layer 107 maybe formed on the upper portion or the lower portion of the upperelectrode 105. If the conductive layer 107 is formed on the lowerportion of the upper electrode 105, the conductive layer 106 is formedon the lower portion of the lower electrode 102. If the conductive layer107 is formed on the upper portion of the upper electrode 105, theconductive layer 106 may be formed on the upper portion or the lowerportion of the lower electrode 102.

FIG. 2 is a diagram illustrating an operation of vapor depositing aconductive material adjacent to a resonance unit 201. Referring to FIG.2, a resonance apparatus includes the resonance unit 201, connectionunits 202 and 203, and conductive materials 204 and 205.

The connection units 202 and 203 may connect the resonance apparatus toan external device, using an upper electrode and a lower electrode. Forexample, the external device may include a transmission device thattransmits a signal and a receiving device that receives the signaltransmitted from the transmission device. The upper electrode may beincluded in both the resonance unit 201 and the connection unit 202. Thelower electrode may be included in both the resonance unit 201 and theconnection unit 203.

In more detail, the resonance apparatus includes a conductive layerformed by vapor depositing a conductive material adjacent to theresonance unit 201. Accordingly, the conductive layer is disposedadjacent to the resonance unit 201. The conductive layer may reduce anelectrode resistance generated by the connection units 202 and 203without affecting an acoustic wave generated by the resonance unit 201.

For example, the resonance apparatus may include a first conductivelayer formed by vapor depositing the conductive material 204 as close aspossible to the resonance unit 201, namely, the upper electrode of theresonance unit 201. In more detail, the conductive material 204 may bevapor deposited in a region corresponding to an interface between theresonance unit 201 and the connection unit 202, within an entire regionof the connection unit 202. That is, the conductive material 204 may notbe vapor deposited within a region of the resonance unit 201.

Therefore, the resonance apparatus may reduce a loss of the acousticwave by vapor depositing Mo, Ru, W, and/or other conductive materialsknown to one of ordinary skill in the art, on the resonance unit 201,which corresponds to the upper electrode of the resonance unit 201.Also, the resonance apparatus may reduce an electrical loss of theconnection unit 202 by vapor depositing the conductive material 204 atthe upper electrode.

In another example, the resonance apparatus may include a secondconductive layer formed by vapor depositing the conductive material 205as close as possible to the resonance unit 201, namely, the lowerelectrode of the resonance unit 201. In more detail, the conductivematerial 205 may be vapor deposited in a region corresponding to aninterface between the resonance unit 201 and the connection unit 203,within an entire region of the connection unit 203. That is, theconductive material 205 may not be vapor deposited within a region ofthe resonance unit 201.

Therefore, the resonance apparatus may reduce a loss of the acousticwave by vapor depositing Mo, Ru, W, and/or other conductive materialsknown to one of ordinary skill in the art, on the resonance unit 201,which corresponds to the lower electrode. Also, the resonance apparatusmay reduce an electrical loss of the connection unit 203 by vapordepositing the conductive material 205 at the lower electrode.

In still another example, the resonance apparatus may include the firstconductive layer formed by vapor depositing the conductive material 204as close as possible to the upper electrode of the resonance unit 201,and the second conductive layer formed by vapor depositing theconductive material 205 as close as possible to the lower electrode ofthe resonance unit 201. Thus, the resonance apparatus may reduceelectrical losses of the respective connection units 202 and 203 morethan when the resonance apparatus includes only one of the firstconductive layer and the second conductive layer.

FIG. 3 is a diagram illustrating another example of a resonanceapparatus 300 including a loss compensation layer 308. Referring to FIG.3, the resonance apparatus 300 includes a substrate 301, a lowerelectrode 302, a piezoelectric layer 304, an upper electrode 305,conductive layers 306 and 307, the loss compensation layer 308, and aloss compensation conductive layer 309. A cavity 303 is formed betweenthe lower electrode 302 and the substrate 301.

That is, the resonance apparatus 300 includes the loss compensationlayer 308 and the loss compensation conductive layer 309 in addition tothe elements of the resonance apparatus 100 of FIG. 1. Therefore, thesame elements as in the resonance apparatus 100 of FIG. 1 will not bedescribed again with reference to FIG. 3 for conciseness.

The loss compensation layer 308 is formed on the upper electrode 305.For example, the loss compensation layer 308 may be formed by patterningan upper edge of the upper electrode 305 into a donut shape, or etchinga donut-shaped trench in the upper edge of the upper electrode 305. Inanother example, the loss compensation layer 308 may be formed by vapordepositing a material including Mo, Ru, Au, silicon dioxide (SiO₂),and/or silicon nitride (SiN), on an upper portion of the upper electrode305, and then patterning an upper edge of the material into a donutshape.

In still another example, the loss compensation layer 308 may be formedby doping the upper portion of the upper electrode 305 with apredetermined impurity, and then patterning an upper edge of the upperelectrode 305 doped with the predetermined impurity into a donut shape.The predetermined impurity may include, for example, boron (B),phosphorus (P), arsenic (As), germanium (Ge), stibium (Sb), silicon(Si), and/or Al.

The loss compensation layer 308 may prevent an acoustic wave reflectedfrom the upper portion of the upper electrode 305 from being reflectedto outside the resonance apparatus 300. Thus, the loss compensationlayer 308 may reduce or prevent a loss of the acoustic wave.

The loss compensation conductive layer 309 is formed on the losscompensation layer 308. For example, the loss compensation conductivelayer 309 may be formed by vapor depositing a conductive material on theloss compensation layer 308. The conductive material may include, forexample, Ag, Cu, Au, Al, Ca, W, Zn, Ni, Fe, Pt, carbon steel, lead,grain-oriented electrical steel, manganin, constantan, stainless steel,and/or graphite. In more detail, the loss compensation conductive layer309 may be formed by vapor depositing the conductive material on anupper edge of the loss compensation layer 308, and into a laminatedstructure.

FIG. 4 is a diagram illustrating still another example of a resonanceapparatus 400 including a reflective layer 404. The resonance apparatus400 includes an air-gap cavity structure and a Bragg reflectorstructure. The air-gap cavity structure includes a lower electrode, anupper electrode, and a piezoelectric layer, which are arranged on anupper portion of a substrate, with a predetermined cavity arrangedbetween the substrate and the lower electrode. The Bragg reflectorstructure includes a reflective layer arranged on the upper portion ofthe substrate that reflects an acoustic wave. According to FIG. 4, theresonance apparatus 400 includes a substrate 401, a lower electrode 402,the reflective layer 404, a piezoelectric layer 405, an upper electrode406, and conductive layers 407 and 408. A cavity 403 is formed betweenthe lower electrode 402 and the substrate 401 (or the reflective layer404).

The resonance apparatus 400 includes the reflective layer 404 inaddition to the elements of the resonance apparatus 100 of FIG. 1.Therefore, the same elements as in the resonance apparatus 100 of FIG. 1will not be described again with reference to FIG. 4 for conciseness.

The reflective layer 404 is formed on an upper portion of the substrate401, and in a partial region of the cavity 403 formed at the upperportion of the substrate 401. As shown in FIG. 4, a side of thereflective layer 404 contacts the lower electrode 402, while anotherside of the reflective layer 404 contacts the piezoelectric layer 405.The reflective layer 404 reflects the acoustic wave converted in thepiezoelectric layer 405.

The reflective layer 404 includes a first reflective layer 409 and asecond reflective layer 410. The first reflective layer 409 is formed onan upper portion of the second reflective layer 410. The cavity 403 isformed at an upper portion of the first reflective layer 409. The firstreflective layer 409 includes a relatively lower acoustic impedance thanthe second reflective layer 410. For example, the first reflective layer409 may be made of a silicon oxide (SiO) based material, a SiN-basedmaterial, and/or an aluminum oxide (AlO) based material.

The second reflective layer 410 is formed on the upper portion of thesubstrate 401, and is disposed under a lower portion of the firstreflective layer 409. The second reflective layer 410 includes arelatively higher acoustic impedance than the first reflective layer409. For example, the second reflective layer 410 may be made of Mo, Ru,W, and/or Pt.

The first reflective layer 409 may include a thickness corresponding toa wavelength of a resonance frequency of the resonance apparatus 400.Also, the second reflective layer 410 may include a thicknesscorresponding to the wavelength of the resonance frequency of theresonance apparatus 400. For example, each of the first reflective layer409 and the second reflective layer 410 may include a thicknesscorresponding to approximately ¼ of the wavelength.

The piezoelectric layer 405 is formed on an upper portion of the lowerelectrode 402, and on the upper portion of the substrate 401, asdescribed with reference to FIG. 1. In addition, as shown in FIG. 4, thepiezoelectric layer 405 is formed on an upper portion of the conductivelayer 407.

As shown in FIG. 4, the conductive layer 407 is formed on the upperportion of the lower electrode 402. Alternatively, the conductive layer407 may be formed on a lower portion of the lower electrode 402, asdescribed with reference to FIG. 1.

FIG. 5 is a diagram illustrating yet another example of a resonanceapparatus 500 including a loss compensation layer 509 and a reflectivelayer 504. According to FIG. 5, the resonance apparatus 500 includes asubstrate 501, a lower electrode 502, the reflective layer 504, apiezoelectric layer 505, an upper electrode 506, conductive layers 507and 508, a loss compensation layer 509, and a loss compensationconductive layer 510. A cavity 503 is formed between the lower electrode502 and the substrate 501 (or the reflective layer 504).

The resonance apparatus 500 includes the loss compensation layer 509 andthe loss compensation conductive layer 510 in addition to the elementsof the resonance apparatus 400 of FIG. 4. Therefore, the same elementsas in the resonance apparatus 400 of FIG. 4 will not be described againwith reference to FIG. 5 for conciseness.

The loss compensation layer 509 is formed on the upper electrode 506.For example, the loss compensation layer 509 may be formed by patterningan upper edge of the upper electrode 506 into a donut shape, or etchinga donut-shaped trench in the upper electrode 506. In another example,the loss compensation layer 509 may be formed by vapor depositing amaterial including Mo, Ru, Au, silicon dioxide (SiO₂), and/or siliconnitride (SiN), on an upper portion of the upper electrode 506, and thenpatterning an upper edge of the material into a donut shape.

In still another example, the loss compensation layer 509 may be formedby doping the upper portion of the upper electrode 506 with apredetermined impurity, and then patterning an upper edge of the upperelectrode 506 doped with the predetermined impurity into a donut shape.The predetermined impurity may include, for example, boron (B),phosphorus (P), arsenic (As), germanium (Ge), stibium (Sb), silicon(Si), and/or Al.

The loss compensation layer 509 may prevent an acoustic wave reflectedfrom the upper portion of the upper electrode 506 from being reflectedto outside the resonance apparatus 500. Thus, the loss compensationlayer 509 may reduce or prevent a loss of the acoustic wave.

The loss compensation conductive layer 510 is formed on the losscompensation layer 509. For example, the loss compensation conductivelayer 510 may be formed by vapor depositing a conductive material on theloss compensation layer 509. The conductive material may include, forexample, Ag, Cu, Au, Al, Ca, W, Zn, Ni, Fe, Pt, carbon steel, lead,grain-oriented electrical steel, manganin, constantan, stainless steel,and/or graphite. In more detail, the loss compensation conductive layer510 may be formed by vapor depositing the conductive material on anupper edge of the loss compensation layer 509, and into a laminatedstructure.

Although the loss compensation layer is illustrated as a donut shape inthe examples of FIGS. 3 to 5, the loss compensation layer may include ashape of any of various polygons known to one of ordinary skill in theart.

FIG. 6 is a diagram illustrating still another example of a resonanceapparatus 600. The resonance apparatus 600 includes a structure and aBragg reflector structure. The structure includes a lower electrode, anupper electrode, and a piezoelectric layer, which are arranged on anupper portion of a substrate. The Bragg reflector structure includes areflective layer arranged on the upper portion of the substrate thatreflects an acoustic wave. According to FIG. 6, the resonance apparatus600 includes a substrate 601, a reflective layer 602, a lower electrode603, a piezoelectric layer 604, an upper electrode 605, and first andsecond conductive layers 606 and 607.

The reflective layer 602 is formed on an upper portion of the substrate601, and reflects an acoustic wave toward the piezoelectric layer 604.The reflective layer 602 includes a first reflective layer 608 and asecond reflective layer 609.

The first reflective layer 608 is formed on the second reflective layer609, and is disposed under the lower electrode 603. The secondreflective layer 609 is formed on the upper portion of the substrate601, and is disposed under the first reflective layer 608. The firstreflective layer 608 includes a relatively lower acoustic impedance thanthe second reflective layer 609. The second reflective layer 609includes a relatively higher acoustic impedance than the firstreflective layer 608. Each of the first reflective layer 608 and thesecond reflective layer 609 may include a thickness corresponding to awavelength of a resonance frequency of the resonance apparatus 600. Forexample, the first reflective layer 608 may be made of a SiO-basedmaterial, a SiN-based material, an AlO-based material, and/or anAlN-based material, and the second reflective layer 609 may be made ofMo, Ru, W, and/or Pt.

The lower electrode 603 is formed on an upper portion of the reflectivelayer 602. The lower electrode 603 may be used as an input electrode toinject an electrical signal, such as an RF signal, into thepiezoelectric layer 604, and/or as an output electrode to output anelectrical signal from the piezoelectric layer 604.

The piezoelectric layer 604 is formed on an upper portion of the lowerelectrode 603. The piezoelectric layer 604 converts an electrical signalinput from the lower electrode 603 or the upper electrode 605 into anacoustic wave.

The upper electrode 605 is formed on an upper portion of thepiezoelectric layer 604. The upper electrode 605 may be used as any oneof an input electrode to inject an electrical signal, such as an RFsignal, into the piezoelectric layer 604, and/or an output electrode tooutput an electrical signal from the piezoelectric layer 604.

As shown in FIG. 6, the first and second conductive layers 606 and 607are formed on the upper portion of the lower electrode 603 and an upperportion of the upper electrode 605, respectively. For example, the firstand second conductive layers 606 and 607 may be formed by vapordepositing a conductive material on the upper portion of the lowerelectrode 603 and the upper portion of the upper electrode 605,respectively. The conductive material may include, for example, Ag, Cu,Au, Al, Ca, W, Zn, Ni, Fe, Pt, carbon steel, lead, grain-orientedelectrical steel, manganin, constantan, stainless steel, and/orgraphite.

In more detail, the first and second conductive layers 606 and 607 maybe formed by vapor depositing the conductive material adjacent to aresonance unit corresponding to a portion of the upper electrode 605and/or the lower electrode 603. For example, the first and secondconductive layers 606 and 607 may be formed by vapor depositing theconductive material at an interface between the resonance unit and aconnection unit corresponding to a remaining portion of the upperelectrode 605 and/or the lower electrode 603, such that the conductivematerial is disposed as close as possible to the resonance unit. Theconnection unit may connect the resonance apparatus 600 to an externaldevice, using the upper electrode 605 and the lower electrode 603.

In another example, the first conductive layer 606 may be formed byvapor depositing the conductive material on the upper portion or a lowerportion of the lower electrode 603. In more detail, the first conductivelayer 606 may be formed by vapor depositing the conductive material onthe lower portion of the lower electrode 603 that corresponds to theupper portion of the reflective layer 602. Alternatively, the firstconductive layer 606 may be formed by vapor depositing the conductivematerial on the upper portion of the lower electrode 603 thatcorresponds to a lower portion of the piezoelectric layer 604, as shownin FIG. 6.

In still another example, the second conductive layer 607 may be formedby vapor depositing the conductive material on any the upper portion ora lower portion of the upper electrode 605. In more detail, the secondconductive layer 607 may be formed by vapor depositing the conductivematerial on the lower portion of the upper electrode 605 thatcorresponds to the upper portion of the piezoelectric layer 604.

In yet another example, the first conductive layer 606 may be formed atthe upper electrode 605, while the second conductive layer 607 may beformed at the lower electrode 603. The first conductive layer 606 andthe second conductive layer 607 may be formed by vapor depositing theconductive material so that the first conductive layer 606 and thesecond conductive layer 607 are not shorted with each other.

FIG. 7 is a diagram illustrating yet another example of a resonanceapparatus 700 including a loss compensation layer 708. According to FIG.7, the resonance apparatus 700 includes a substrate 701, a reflectivelayer 702 including first and second reflective layers 710 and 711, alower electrode 703, a piezoelectric layer 704, an upper electrode 705,first and second conductive layers 706 and 707, the loss compensationlayer 708, and a loss compensation conductive layer 709.

The resonance apparatus 700 includes the loss compensation layer 708 andthe loss compensation conductive layer 709 in addition to the elementsof the resonance apparatus 600 of FIG. 6. Therefore, the same elementsas in the resonance apparatus 600 of FIG. 6 will not be described againwith reference to FIG. 7 for conciseness.

As shown in FIG. 7, the first and second conductive layers 706 and 707are formed on a lower portion of the lower electrode 703 and a lowerportion of the upper electrode 705, respectively. Alternatively, thefirst and second conductive layers 706 and 707 may be formed on an upperportion of the lower electrode 703 and an upper portion of the upperelectrode 705, respectively, as shown in FIG. 6.

The loss compensation layer 708 is formed on the upper portion of theupper electrode 705. For example, the loss compensation layer 708 may beformed by patterning an upper edge of the upper electrode 705 into adonut shape, or etching a donut-shaped trench in the upper edge of theupper electrode 705. In another example, the loss compensation layer 708may be formed by vapor depositing a material including Mo, Ru, Au, SiO₂,and/or SiN, on the upper portion of the upper electrode 705, and thenpatterning an upper edge of the material into a donut shape.

In still another example, the loss compensation layer 708 may be formedby doping the upper portion of the upper electrode 705 with apredetermined impurity, and then patterning an upper edge of the upperelectrode 705 doped with the predetermined impurity into a donut shape.The predetermined impurity may include, for example, B, P, As, Ge, Sb,Si, and/or Al.

The loss compensation conductive layer 709 is formed on the losscompensation layer 708. For example, the loss compensation conductivelayer 709 may be formed by vapor depositing a conductive material on theloss compensation layer 708. The conductive material may include Ag, Cu,Au, Al, Ca, W, Zn, Ni, Fe, Pt, carbon steel, lead, grain-orientedelectrical steel, manganin, constantan, stainless steel, and/orgraphite. In more detail, the loss compensation conductive layer 709 maybe formed by vapor depositing the conductive material on an upper edgeof the loss compensation layer 708, and into a laminated structure.

FIG. 8 is a block diagram illustrating an example of a film bulkacoustic filter 800. In FIG. 8, the film bulk acoustic filter 800 may beimplemented using the resonance apparatuses (or resonators) as shown inFIGS. 1 to 7. According to FIG. 8, the film bulk acoustic filter 800includes resonators 801 including a first resonator 807, a secondresonator 808, and an n-th resonator 809, a resonator connection unit802, a pad 803, an electrode connection unit 804, a grounding unit 805,and a conductive layer forming unit 806.

The resonators 801 are formed on an upper portion of a substrate. Atleast one of the resonators 801 may include a loss compensation layerthat may be formed by patterning an edge of an upper electrode into adonut shape. A loss compensation conductive layer may be formed by vapordepositing a conductive material on an upper portion of the losscompensation layer. The conductive material may include, for example,Ag, Cu, Au, Al, Ca, W, Zn, Ni, Fe, Pt, carbon steel, lead,grain-oriented electrical steel, manganin, constantan, stainless steel,and/or graphite.

The resonator connection unit 802 connects the resonators 801 to oneanother and to the pad 803, the electrode connection unit 804, and/orthe grounding unit 805. The pad 803 is formed on the upper portion ofthe substrate, and provides a connection to an external terminal. Inmore detail, the pad 803 may connect the external terminal to an upperelectrode and/or a lower electrode of at least one of the resonators 801that are not connected to the grounding unit 805.

The electrode connection unit 804 may connect an upper electrode and alower electrode of at least one of the resonators 801, to each other.For example, the electrode connection unit 804 may connect an upperelectrode of a first resonator 807 to a lower electrode of at least oneof a second resonator 808 to an N-th resonator 809. In a similar manner,the electrode connection unit 804 may connect a lower electrode of thefirst resonator 807 to an upper electrode of at least one of the secondresonator 808 to the N-th resonator 809.

The grounding unit 805 may connect an upper electrode and/or a lowerelectrode of at least one of the resonators 801, to ground. For example,the grounding unit 805 may connect the upper electrode of the firstresonator 807 and the lower electrode of the second resonator 808, toground, whereas the pad 803 may connect a lower electrode of the firstresonator 807 and the upper electrode of the second resonator 808, tothe external terminal.

The conductive layer forming unit 806 may form a conductive layeradjacent to at least one of the resonators 801 and on the resonatorconnection unit 802, the pad 803, the electrode connection unit 804,and/or the grounding unit 805, to reduce an electrical loss of theseelements. The conductive layer may be made of a conductive materialincluding, for example, Ag, Cu, Au, Al, Ca, W, Zn, Ni, Fe, Pt, carbonsteel, lead, grain-oriented electrical steel, manganin, constantan,stainless steel, and/or graphite. Accordingly, the film bulk acousticfilter 800 may reduce or remove a loss of a quality factor (Q factor)and an insertion loss of at least one of the resonators 801.

FIG. 9 is a diagram illustrating another example of a film bulk acousticfilter 900. In FIG. 9, the film bulk acoustic filter 900 includesresonators, a resonator connection unit 901, a grounding unit 902, and apad 903.

The resonator connection unit 901 connects the resonators to one anotherand to the grounding unit 902 and/or the pad 903. The resonatorconnection unit 901 may be made of a conductive material.

The grounding unit 902 may be formed by vapor depositing a conductivematerial on an edge of a substrate. The grounding unit 902 may connectan upper electrode and/or a lower electrode of at least one of theresonators, to ground.

The pad 903 may be single or plural in number, and may be formed byvapor depositing a conductive material on a partial region of thesubstrate. The pad 903 may connect an external terminal to an upperelectrode and/or a lower electrode of at least one of the resonatorsthat are not connected to the grounding unit 902.

FIG. 10 is a diagram illustrating an example of an electrode connectionunit in a film bulk acoustic filter. According to FIG. 10, the electrodeconnection unit connects an upper electrode and a lower electrode of atleast one of resonators of the film bulk acoustic filter, to each other.

For example, the electrode connection unit connects an upper electrode1003 of a first resonator 1001 to a lower electrode 1004 of a secondresonator 1002, using a conductive material 1005. That is, the electrodeconnection unit connects an upper electrode and a lower electrode ofdifferent resonators, to each other. Thus, the electrode connection unitmay reduce an electrical resistance generated during a connection.

In this example, the conductive material may include a high conductivitymaterial including a conductivity of about 1×10⁵σS/m or higher. Forexample, the conductive material may include Ag, Cu, Au, Al, Ca, W, Zn,Ni, Fe, Pt, carbon steel, lead, grain-oriented electrical steel,manganin, constantan, stainless steel, and/or graphite.

FIG. 11 is a flowchart illustrating an example of a method ofmanufacturing a resonance apparatus. The resonance apparatus includes anair-gap cavity structure.

Referring to FIG. 11, in operation 1101, a lower electrode is formed tobe separated by a predetermined distance from an upper portion of asubstrate. For example, the lower electrode may be made of Mo, Ru, W,and/or other conductive materials known to one of ordinary skill in theart. The lower electrode may be used as an input electrode to inject anelectrical signal, such as an RF signal, into a piezoelectric layer,and/or as an output electrode to output an electrical signal from thepiezoelectric layer. Accordingly, a cavity is formed between the lowerelectrode and the substrate. Therefore, the lower electrode is separatedfrom the substrate by as much as the cavity. The substrate may be dopedwith Si. For example, the substrate may include a Si wafer.

In operation 1102, a piezoelectric layer is formed on an upper portionof the lower electrode. For example, the piezoelectric layer may beformed by vapor depositing AlN, ZnO, or lead zirconate titanate on theupper portion of the lower electrode. The piezoelectric layer convertsan electrical signal input from the lower electrode or an upperelectrode into an acoustic wave.

In more detail, when a temporally changing electric field is induced,the piezoelectric layer converts the electrical signal into a physicaloscillation. In addition, the piezoelectric layer converts the physicaloscillation into the acoustic wave. The piezoelectric layer generatesthe acoustic wave to be a bulk acoustic wave based on the inducedelectric field in a same direction as an oscillation direction in anoriented piezoelectric film.

In operation 1103, the upper electrode is formed on an upper portion ofthe piezoelectric layer. For example, the upper electrode may be formedby vapor depositing Mo, Ru, W, and/or other conductive materials knownto one of ordinary skill in the art, on the upper portion of thepiezoelectric layer. The upper electrode may be used as an inputelectrode to inject an electrical signal, such as an RF signal, into thepiezoelectric layer, and/or as an output electrode to output anelectrical signal from the piezoelectric layer.

In operation 1104, a conductive layer is formed on the upper electrodeand/or the lower electrode. For example, the conductive layer may beformed by vapor depositing a conductive material on the upper electrodeand/or the lower electrode. The conductive material may include, forexample, a high conductivity material including a conductivity of about1×10⁵σS/m or higher. For example, the conductive material may includeAg, Cu, Au, Al, Ca, W, Zn, Ni, Fe, Pt, carbon steel, lead,grain-oriented electrical steel, manganin, constantan, stainless steel,and/or graphite.

For example, a first conductive layer may be formed by vapor depositingthe conductive material on a lower portion of the lower electrode thatcorresponds to the upper portion of the substrate. Alternatively, thefirst conductive layer may be formed by vapor depositing the conductivematerial on the upper portion of the lower electrode that corresponds toa lower portion of the piezoelectric layer.

In this example, a second conductive layer may be formed by vapordepositing the conductive material on an upper portion or a lowerportion of the upper electrode. In more detail, the second conductivelayer may be formed by vapor depositing vapor the conductive material onthe lower portion of the upper electrode that corresponds to the upperportion of the piezoelectric layer.

In another example, the first conductive layer may be formed at theupper electrode, and the second conductive layer may be formed at thelower electrode. In still another example, the first conductive layerand the second conductive layer may be formed by vapor depositing theconductive material so the first conductive layer and the secondconductive layer are not shorted with each other. For example, the firstconductive layer may be formed on the upper portion of the lowerelectrode, while the second conductive layer may be formed on the upperportion of the upper electrode. Alternatively, the first conductivelayer may be formed on the lower portion of the lower electrode, whilethe second conductive layer may be formed on the upper portion or thelower portion of the upper electrode.

In operation 1105, a loss compensation layer is formed on the upperelectrode. For example, the loss compensation layer may be formed bypatterning an upper edge of the upper electrode into a donut shape, oretching a donut-shaped trench in the upper edge of the upper electrode.In another example, the loss compensation layer may be formed by vapordepositing a material including Mo, Ru, Au, SiO₂, and/or SiN, on theupper portion of the upper electrode, and then patterning an upper edgeof the material into a donut shape.

In still another example, the loss compensation layer may be formed bydoping the upper portion of the upper electrode with a predeterminedimpurity, and then patterning an upper edge of the upper electrode dopedwith the predetermined impurity into a donut shape. The predeterminedimpurity may include, for example, B, P, As, Ge, Sb, Si, and/or Al.

Thus, the loss compensation layer may prevent an acoustic wave reflectedfrom the upper portion of the upper electrode from being reflected tooutside of the resonance apparatus. Therefore, the loss compensationlayer may reduce or prevent a loss of the acoustic wave.

In operation 1106, a loss compensation conductive layer is formed on theloss compensation layer. For example, the loss compensation conductivelayer may be formed by vapor depositing a conductive material on theloss compensation layer. The conductive material may include, forexample, Ag, Cu, Au, Al, Ca, W, Zn, Ni, Fe, Pt, carbon steel, lead,grain-oriented electrical steel, manganin, constantan, stainless steel,and/or graphite. In more detail, the loss compensation conductive layermay be formed by vapor depositing the conductive material on an upperedge of the loss compensation layer, and into a laminated structure.

FIG. 12 is a flowchart illustrating another example of a method ofmanufacturing a resonance apparatus. The resonance apparatus includes anair-gap cavity structure and a Bragg reflector structure.

That is, the method of manufacturing the resonance apparatus includesforming the Bragg reflector structure in addition to the operations ofthe method of manufacturing the resonance apparatus of FIG. 11.Therefore, the same operations as in the method of manufacturing theresonance apparatus of FIG. 11 will not be described in detail withreference to FIG. 12 for conciseness.

Referring to FIG. 12, in operation 1201, a lower electrode is formed ata predetermined distance from an upper portion of a substrate.

In operation 1202, a piezoelectric layer is formed on an upper portionof the lower electrode.

In operation 1023, a reflective layer is formed on the upper portion ofthe substrate. The reflective layer reflects an acoustic wave convertedby the piezoelectric layer. The reflective layer may include a thicknesscorresponding to a wavelength of a resonance frequency of the resonanceapparatus. The reflective layer may include a first reflective layer anda second reflective layer. For example, the second reflective layer maybe formed by vapor depositing Mo, Ru, W, and/or Pt, on the upper portionof the substrate. In addition, the first reflective layer may be formedby vapor depositing a SiO-based material, a SiN-based material, anAlO-based material, and/or an AlN-based material, on an upper portion ofthe second reflective layer. A cavity is formed at an upper portion ofthe first reflective layer. Accordingly, the first reflective layer mayinclude a relatively lower acoustic impedance than the second reflectivelayer.

In operation 1204, the upper electrode is formed on an upper portion ofthe piezoelectric layer.

In operation 1205, a conductive layer is formed on the upper electrodeand/or the lower electrode.

In operation 1206, a loss compensation layer is formed on the upperelectrode.

In operation 1207, a loss compensation conductive layer is formed on theloss compensation layer.

FIG. 13 is a flowchart illustrating still another method ofmanufacturing a resonance apparatus. The resonance apparatus includes astructure and a Bragg reflector structure.

That is, the method of manufacturing the resonance apparatus includesforming the Bragg reflector structure in addition to the operations ofthe method of manufacturing the resonance apparatus of FIG. 11.Therefore, the same operations as in the method of manufacturing theresonance apparatus of FIG. 11 will not be described in detail withreference to FIG. 13 for conciseness.

Referring to FIG. 13, in operation 1301, a reflective layer is formed onan upper portion of a substrate. The reflective layer reflects anacoustic wave converted by a piezoelectric layer. The reflective layermay include a thickness corresponding to a wavelength of a resonancefrequency of the resonance apparatus. The reflective layer may include afirst reflective layer and a second reflective layer. For example, thesecond reflective layer may be formed by vapor depositing Mo, Ru, W,and/or Pt, on the upper portion of the substrate. In addition, the firstreflective layer may be formed by vapor depositing a SiO-based material,a SiN-based material, an AlO-based material, and an AlN-based material,on an upper portion of the second reflective layer. Accordingly, thefirst reflective layer may include a relatively lower acoustic impedancethan the second reflective layer.

In operation 1302, a lower electrode is formed on an upper portion ofthe reflective layer.

In operation 1303, a piezoelectric layer is formed on an upper portionof the lower electrode.

In operation 1304, an upper electrode is formed on an upper portion ofthe piezoelectric layer.

In operation 1305, a conductive layer is formed on the upper electrodeand/or the lower electrode.

In operation 1306, a loss compensation layer is formed on the upperelectrode.

In operation 1307, a loss compensation conductive layer is formed on theloss compensation layer.

The units described herein may be implemented using hardware componentsand software components. For example, the hardware components mayinclude microphones, amplifiers, band-pass filters, audio to digitalconvertors, and processing devices. A processing device may beimplemented using one or more general-purpose or special purposecomputers, such as, for example, a processor, a controller and anarithmetic logic unit, a digital signal processor, a microcomputer, afield programmable array, a programmable logic unit, a microprocessor orany other device capable of responding to and executing instructions ina defined manner. The processing device may run an operating system (OS)and one or more software applications that run on the OS. The processingdevice also may access, store, manipulate, process, and create data inresponse to execution of the software. For purpose of simplicity, thedescription of a processing device is used as singular; however, oneskilled in the art will appreciated that a processing device may includemultiple processing elements and multiple types of processing elements.For example, a processing device may include multiple processors or aprocessor and a controller. In addition, different processingconfigurations are possible, such a parallel processors.

The software may include a computer program, a piece of code, aninstruction, or some combination thereof, that independently orcollectively instruct or configure the processing device to operate asdesired. Software and data may be embodied permanently or temporarily inany type of machine, component, physical or virtual equipment, computerstorage medium or device, or in a propagated signal wave capable ofproviding instructions or data to or being interpreted by the processingdevice. The software also may be distributed over network coupledcomputer systems so that the software is stored and executed in adistributed fashion. The software and data may be stored by one or morecomputer readable recording mediums. The computer readable recordingmedium may include any data storage device that can store data which canbe thereafter read by a computer system or processing device. Examplesof the non-transitory computer readable recording medium includeread-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetictapes, floppy disks, and optical data storage devices. Also, functionalprograms, codes, and code segments that accomplish the examplesdisclosed herein can be easily construed by programmers skilled in theart to which the examples pertain based on and using the flow diagramsand block diagrams of the figures and their corresponding descriptionsas provided herein.

A number of examples have been described above. Nevertheless, it will beunderstood that various modifications may be made. For example, suitableresults may be achieved if the described techniques are performed in adifferent order and/or if components in a described system,architecture, device, or circuit are combined in a different mannerand/or replaced or supplemented by other components or theirequivalents.

What is claimed is:
 1. A resonance apparatus comprising: a lowerelectrode formed at a predetermined distance from a substrate; apiezoelectric layer formed on the lower electrode; an upper electrodeformed on the piezoelectric layer; and a conductive layer formed on theupper electrode or the lower electrode.
 2. The resonance apparatus ofclaim 1, wherein the conductive layer is formed adjacent to a resonanceunit corresponding to the upper electrode and/or the lower electrode. 3.The resonance apparatus of claim 1, further comprising: a losscompensation layer formed on the upper electrode.
 4. The resonanceapparatus of claim 3, further comprising: a loss compensation conductivelayer formed on the loss compensation layer.
 5. The resonance apparatusof claim 4, wherein the loss compensation conductive layer comprisessilver (Ag), or copper (Cu), or gold (Au), or aluminum (Al), or calcium(Ca), or tungsten (W), or zinc (Zn), or nickel (Ni), or iron (Fe), orplatinum (Pt), or carbon steel, or lead, or grain-oriented electricalsteel, or manganin, or constantan, or stainless steel, or graphite, orany combination thereof.
 6. The resonance apparatus of claim 3, whereinthe loss compensation layer comprises molybdenum (Mo), or ruthenium(Ru), or gold (Au), or silicon dioxide (SiO₂), or silicon nitride (SiN),or any combination thereof.
 7. The resonance apparatus of claim 1,further comprising: a reflective layer formed on the substrate.
 8. Theresonance apparatus of claim 7, wherein the reflective layer comprises:a first reflective layer; and a second reflective layer formed on thesubstrate, the first reflective layer being formed on the secondreflective layer and comprising a relatively lower acoustic impedancethan the second reflective layer.
 9. The resonance apparatus of claim 8,wherein: the first reflective layer comprises a silicon oxide (SiO)based material, a silicon nitride (SiN) based material, or an aluminumoxide (AlO) based material, or any combination thereof; and the secondreflective layer comprises molybdenum (Mo), or ruthenium (Ru), ortungsten (W), or platinum (Pt), or any combination thereof.
 10. Theresonance apparatus of claim 8, wherein each of the first reflectivelayer and the second reflective layer comprises a thicknesscorresponding to a wavelength of a resonance frequency of the resonanceapparatus.
 11. The resonance apparatus of claim 7, wherein the lowerelectrode is formed on the reflective layer.
 12. The resonance apparatusof claim 1, wherein the conductive layer comprises silver (Ag), orcopper (Cu), or gold (Au), or aluminum (Al), or calcium (Ca), ortungsten (W), or zinc (Zn), or nickel (Ni), or iron (Fe), or platinum(Pt), or carbon steel, or lead, or grain-oriented electrical steel, ormanganin, or constantan, or stainless steel, or graphite, or anycombination thereof.
 13. The resonance apparatus of claim 1, wherein theconductive layer is formed on an upper portion or a lower portion of theupper electrode or the lower electrode.
 14. The resonance apparatus ofclaim 1, further comprising: another conductive layer formed on theupper electrode, wherein the conductive layer is formed on the lowerelectrode.
 15. The resonance apparatus of claim 14, wherein: the otherconductive layer is formed on an upper portion of the upper electrode ifthe conductive layer is formed on an upper portion of the lowerelectrode; and the other conductive layer is formed on the upper portionor a lower portion of the upper electrode if the conductive layer isformed on a lower portion of the lower electrode.
 16. A film bulkacoustic filter comprising: resonators formed on a substrate; anelectrode connection unit configured to connect an upper electrode to alower electrode, of at least one of the resonators; a grounding unitconfigured to connect the upper electrode and the lower electrode toground; a pad formed on the substrate and configured to connect theupper electrode and the lower electrode to an external terminal; and aconductive layer forming unit configured to form a conductive layer onthe electrode connection unit, or the grounding unit, or the pad, or anycombination thereof.
 17. The film bulk acoustic filter of claim 16,wherein the at least one of the resonators comprises a loss compensationlayer formed on an upper electrode.
 18. The film bulk acoustic filter ofclaim 17, wherein the at least one of the resonators comprises a losscompensation conductive layer formed on the loss compensation layer. 19.A method of manufacturing a resonance apparatus, comprising: forming alower electrode at a predetermined distance from a substrate; forming apiezoelectric layer on the lower electrode; forming an upper electrodeon the piezoelectric layer; and forming a conductive layer on the upperelectrode or the lower electrode.
 20. The method of claim 19, whereinthe forming of the conductive layer comprises: vapor depositing aconductive material on the upper electrode or the lower electrode andadjacent to a resonance unit corresponding to the upper electrode and/orthe lower electrode.
 21. The method of claim 19, further comprising:forming a loss compensation layer on the upper electrode.
 22. The methodof claim 21, wherein the forming of the loss compensation layercomprises: patterning an edge of the upper electrode; or etching atrench in the upper electrode.
 23. The method of claim 21, wherein theforming of the loss compensation layer comprises: vapor depositing amaterial comprising molybdenum (Mo), or ruthenium (Ru), or gold (Au), orsilicon dioxide (SiO₂), or silicon nitride (SiN), or any combinationthereof, on the upper electrode; and patterning an edge of the material.24. The method of claim 21, wherein the forming of the loss compensationlayer comprises: doping a portion of the upper electrode with apredetermined impurity; and patterning an edge of the doped upperelectrode.
 25. The method of claim 24, wherein the predeterminedimpurity comprises boron (B), or phosphorus (P), or arsenic (As), orgermanium (Ge), or stibium (Sb), or silicon (Si), or aluminum (Al), orany combination thereof.
 26. The method of claim 21, further comprising:forming a loss compensation conductive layer by vapor depositing aconductive material on the loss compensation layer.
 27. The method ofclaim 19, further comprising: forming a reflective layer on thesubstrate.
 28. The method of claim 27, wherein the forming of thereflective layer: forming a first reflective layer; and forming a secondreflective layer on the substrate, the first reflective layer beingformed on the second reflective layer and comprising a relatively loweracoustic impedance than the second reflective layer.
 29. The method ofclaim 27, wherein the lower electrode is formed on the reflective layer.30. The method of claim 19, further comprising: forming anotherconductive layer on the upper electrode, wherein the conductive layer isformed on the lower electrode.